Jaeger-LeCoultre Duomètre Unique Travel Time

What do Patek Philippe, Audemars Piguet and Vacheron Constantin all have in common? Yes, they do make up the top three best watchmakers in the world, but there's something else they share: they have all sourced movements from Jaeger-LeCoultre. Originating as an amalgam of car instrument manufacturer Jaeger and Paris-based watchmaker LeCoultre, Jaeger-LeCoultre's list of accolades includes the invention of over 1,200 different calibres and 400 patents.

With the world's smallest movement, the near-perpetual clock and even the invention of the first instrument to measure a micron to the watchmaker's name, it's no wonder the top manufacturers come to Jaeger-LeCoultre for expertise. And here's yet another reason: the limited edition Jaeger-LeCoultre Duomètre Unique Travel Time.

Watches with the capability of displaying multiple time zones have existed since the 18th century, helping travellers cope with changing times across states and countries. All very well and good, but these watches were simple, with one dial for home and one for local, and required the user to know the time difference in order to set them.

A solution came about in the 1930s thanks to a watchmaker called Louis Cottier. He developed a world timer mechanism that ringed the dial with twenty-four cities, one for each hour of the day, which could each be selected to adjust the time shown on the main display. This meant the user was not required to know which time zone they needed, merely selecting the city itself and letting the watch do the rest. Cottier's movement was so good that it eventually found its way into the Patek Philippe and Vacheron Constantin world timers of the time.

Twin dials show home and local time in any combination you like!

This particular solution brought about problems of its own, however: the first was the requirement to know the time differences of cities not highlighted on the dial. New York was demarcated as the city for GMT minus five hours for example, but what about Miami, or Washington DC?

The second problem is that, while twenty-four time zones is a lot of time zones, they're not all the time zones. There are in fact thirty-eight in total, including Indian Standard Time, which is offset by five and a half hours from GMT, not possible on a standard world timer. And it gets even more complicated: In India, Bombay time is GMT plus four hours and fifty-one minutes, Calcutta plus five hours and fifty-four minutes. So, what's the solution?

Enter the Jaeger-LeCoultre Unique Travel Time. And it certainly is unique. You get two time displays, home on the right and local on the left—which, but the way, uses a jumping hour display for quick reading—but you don't have to memorise anything. It probably hasn't gone unnoticed that there's a great big globe at the bottom of the dial, too, complete with spherical relief, and this is the source of this travel timer's cleverness.

You see, there's no need to remember which city has what time zone here. All you need to do is go forwards or backwards—whichever's quickest—with the pushers, and align the relevant city with the red arrow at the bottom. If we start at GMT, for example, and want to set the local display to Miami time, we click the globe around until the red arrow points at Miami. And that's it! Done!

Choose your time zone from the handy globe set in the dial

You even get a handy shaded day/night indicator on the GMT ring that shows you which half of the globe is darkness, which somehow floats and moves independently when setting.

And if there are any doubts about which time zone you're looking for, there's a handy city list on the back, same as you'd get on the dial of a traditional world timer.

But what about the countries with non-integer time zones, like India? Simple. Pull out the crown one click and adjust local time however you like. While this does require a knowledge of the local time difference, it's unparalleled by other world timers. It's so flexible, you can even set it to zero and use it as timer if you really want to.

The Dual Wing concept maximises accuracy across the dials

The downsides? Well, while I've been talking, you may have spotted that the globe only shows the northern hemisphere. For the southern hemisphere—Sydney, for example—you'll need to refer to the list on the case back to find the time difference, or use the internet. Maybe Jaeger-LeCoultre could look into having the southern hemisphere appear through the case back or something.

Back to the positive. The last feature of the dial is the power reserve indicator. You'll notice there are two. Why? Because the calibre 383 that powers this watch is a 498-part monster with some particularly trick features.

The movement is based on the 'Dual Wing' concept Jaeger-LeCoultre introduced to increase accuracy. As the functionality of this watch is power-hungry, more torque is needed to achieve the fifty hours of reserve Jaeger-LeCoultre wanted. But simply adding a larger mainspring is not necessarily the answer, as torque decreases over time as a mainspring unwinds, a phenomenon that becomes more apparent as the mainspring gets larger.

Two mainsprings work together to power home and local time

The solution is unique and beautifully simple: the home time and local time displays each have their own mainspring, and thus their own power reserve displays. On a roll with clever, simple ideas, Jaeger-LeCoultre also figured that they could have the crown turn one way to wind one mainspring, and back again to wind the other. Genius.

The cherry on the cake, and a continuation of the accuracy theme, is the calibre 383's ability to stop and reset the central seconds hand when the crown is pulled, for precision setting. Jaeger-LeCoultre didn't need to add that feature, but they did. Of course they did.

It's no wonder that the world's best watchmakers turn to Jaeger-LeCoultre for expertise. This is a hugely complicated movement that packs in the features, and yet it still fits into a 42mm case that stays on the sensible side of thick. And not only is it functional, but beautiful too, especially this limited edition with its hand-engraved échoppé dial. Patek Philippe, Audemars Piguet and Vacheron Constantin may get all the glory, but it's watches like this from Jaeger-LeCoultre that truly deserve it.